The invention relates to a stuffing box seal for fittings, more particularly for valves or the like, in which deformable sealing material is contained in the stuffing box chamber between a casing wall and another component, for example a spindle.
The lid member situated in the fluid-biased chamber of stop valves is connected by means of a spindle to the outer drive. A bushing through which the rotatably and/or axially movable spindle extends through the casing chamber is sealed by means of a stuffing box seal. In a stuffing box seal of this kind deformable material, exposed to the pressure of a gland device, is situated in the stuffing box chamber in order to prevent or reduce to a minimum any leakages.
Asbestos is predominantly used as sealing material in stuffing box seals of this kind, particularly when the seals are exposed to elevated temperatures. Special substances, such as graphite, are added to the asbestos to improve its anti-friction properties. It is also known to use pure carbon as a sealing material for particularly difficult sealing problems.
In the stuffing box chamber, the contact surfaces between the casing and the spindle form local elements with the sealing material and its admixtures in the presence of an electrolyte. These contact surfaces are therefore subject to attack due to corrosion and can be prematurely destroyed.